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-rw-r--r--Documentation/arm64/silicon-errata.rst2
-rw-r--r--arch/arm64/Kconfig17
-rw-r--r--arch/arm64/kernel/cpu_errata.c10
-rw-r--r--arch/arm64/kernel/cpufeature.c5
-rw-r--r--arch/arm64/kernel/topology.c32
-rw-r--r--arch/arm64/tools/cpucaps1
6 files changed, 64 insertions, 3 deletions
diff --git a/Documentation/arm64/silicon-errata.rst b/Documentation/arm64/silicon-errata.rst
index 33b04db8408f..fda97b3fcf01 100644
--- a/Documentation/arm64/silicon-errata.rst
+++ b/Documentation/arm64/silicon-errata.rst
@@ -52,6 +52,8 @@ stable kernels.
| Allwinner | A64/R18 | UNKNOWN1 | SUN50I_ERRATUM_UNKNOWN1 |
+----------------+-----------------+-----------------+-----------------------------+
+----------------+-----------------+-----------------+-----------------------------+
+| ARM | Cortex-A510 | #2457168 | ARM64_ERRATUM_2457168 |
++----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A510 | #2064142 | ARM64_ERRATUM_2064142 |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A510 | #2038923 | ARM64_ERRATUM_2038923 |
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 571cc234d0b3..9fb9fff08c94 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -917,6 +917,23 @@ config ARM64_ERRATUM_1902691
If unsure, say Y.
+config ARM64_ERRATUM_2457168
+ bool "Cortex-A510: 2457168: workaround for AMEVCNTR01 incrementing incorrectly"
+ depends on ARM64_AMU_EXTN
+ default y
+ help
+ This option adds the workaround for ARM Cortex-A510 erratum 2457168.
+
+ The AMU counter AMEVCNTR01 (constant counter) should increment at the same rate
+ as the system counter. On affected Cortex-A510 cores AMEVCNTR01 increments
+ incorrectly giving a significantly higher output value.
+
+ Work around this problem by returning 0 when reading the affected counter in
+ key locations that results in disabling all users of this counter. This effect
+ is the same to firmware disabling affected counters.
+
+ If unsure, say Y.
+
config CAVIUM_ERRATUM_22375
bool "Cavium erratum 22375, 24313"
default y
diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index 0f7e9087d900..53b973b6059f 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -656,6 +656,16 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
ERRATA_MIDR_REV_RANGE(MIDR_CORTEX_A510, 0, 0, 2)
},
#endif
+#ifdef CONFIG_ARM64_ERRATUM_2457168
+ {
+ .desc = "ARM erratum 2457168",
+ .capability = ARM64_WORKAROUND_2457168,
+ .type = ARM64_CPUCAP_WEAK_LOCAL_CPU_FEATURE,
+
+ /* Cortex-A510 r0p0-r1p1 */
+ CAP_MIDR_RANGE(MIDR_CORTEX_A510, 0, 0, 1, 1)
+ },
+#endif
#ifdef CONFIG_ARM64_ERRATUM_2038923
{
.desc = "ARM erratum 2038923",
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 907401e4fffb..af4de817d712 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -1870,7 +1870,10 @@ static void cpu_amu_enable(struct arm64_cpu_capabilities const *cap)
pr_info("detected CPU%d: Activity Monitors Unit (AMU)\n",
smp_processor_id());
cpumask_set_cpu(smp_processor_id(), &amu_cpus);
- update_freq_counters_refs();
+
+ /* 0 reference values signal broken/disabled counters */
+ if (!this_cpu_has_cap(ARM64_WORKAROUND_2457168))
+ update_freq_counters_refs();
}
}
diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c
index 869ffc4d4484..ad2bfc794257 100644
--- a/arch/arm64/kernel/topology.c
+++ b/arch/arm64/kernel/topology.c
@@ -296,12 +296,25 @@ core_initcall(init_amu_fie);
static void cpu_read_corecnt(void *val)
{
+ /*
+ * A value of 0 can be returned if the current CPU does not support AMUs
+ * or if the counter is disabled for this CPU. A return value of 0 at
+ * counter read is properly handled as an error case by the users of the
+ * counter.
+ */
*(u64 *)val = read_corecnt();
}
static void cpu_read_constcnt(void *val)
{
- *(u64 *)val = read_constcnt();
+ /*
+ * Return 0 if the current CPU is affected by erratum 2457168. A value
+ * of 0 is also returned if the current CPU does not support AMUs or if
+ * the counter is disabled. A return value of 0 at counter read is
+ * properly handled as an error case by the users of the counter.
+ */
+ *(u64 *)val = this_cpu_has_cap(ARM64_WORKAROUND_2457168) ?
+ 0UL : read_constcnt();
}
static inline
@@ -328,7 +341,22 @@ int counters_read_on_cpu(int cpu, smp_call_func_t func, u64 *val)
*/
bool cpc_ffh_supported(void)
{
- return freq_counters_valid(get_cpu_with_amu_feat());
+ int cpu = get_cpu_with_amu_feat();
+
+ /*
+ * FFH is considered supported if there is at least one present CPU that
+ * supports AMUs. Using FFH to read core and reference counters for CPUs
+ * that do not support AMUs, have counters disabled or that are affected
+ * by errata, will result in a return value of 0.
+ *
+ * This is done to allow any enabled and valid counters to be read
+ * through FFH, knowing that potentially returning 0 as counter value is
+ * properly handled by the users of these counters.
+ */
+ if ((cpu >= nr_cpu_ids) || !cpumask_test_cpu(cpu, cpu_present_mask))
+ return false;
+
+ return true;
}
int cpc_read_ffh(int cpu, struct cpc_reg *reg, u64 *val)
diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps
index 779653771507..63b2484ce6c3 100644
--- a/arch/arm64/tools/cpucaps
+++ b/arch/arm64/tools/cpucaps
@@ -67,6 +67,7 @@ WORKAROUND_1902691
WORKAROUND_2038923
WORKAROUND_2064142
WORKAROUND_2077057
+WORKAROUND_2457168
WORKAROUND_TRBE_OVERWRITE_FILL_MODE
WORKAROUND_TSB_FLUSH_FAILURE
WORKAROUND_TRBE_WRITE_OUT_OF_RANGE